Liquid crystal display and method for manufacturing the same

ABSTRACT

A liquid crystal display (LCD) device and a method for manufacturing the same are discussed. According to an embodiment, the liquid crystal display device includes a first substrate and a second substrate facing each other, wherein each of the first and second substrates includes pixel regions to form a matrix, a black matrix layer arranged in a region other than the pixel regions gate lines and data lines arranged in a portion corresponding to the black matrix layer spacers arranged in predetermined portions provided on the black matrix layer wherein each of the plurality of spacers includes one or more balls, and a solid to adhere the one or more balls to the first or second substrate, and a liquid crystal layer filled between the first substrate and the second substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/233,355 filed on Sep. 18, 2008 now U.S. Pat. No. 8,040,485, whichclaims the priority to Korean Patent Application No. 10-2007-0096482,filed on Sep. 21, 2007. The entire contents of each of theseapplications are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display (LCD) device.More particularly, the present invention relates to a liquid crystaldisplay (LCD) device and a method for manufacturing the same, wherein,after balls are formed in an ink-jetting manner, a solid is left behindon the surface where the balls are formed, thus causing improvement ofthe adhesion force between the balls and substrates.

2. Discussion of the Related Art

With the progress of information-dependent society, the demand forvarious display devices has increased. To meet such a demand, effortshave recently been made to research flat panel display devices such asliquid crystal displays (LCDs), plasma display panels (PDPs),electro-luminescent displays (ELDs) and vacuum fluorescent displays(VFDs). Some types of such flat panel displays are being practicallyapplied to various appliances for display purposes.

Of these, LCDs are currently most widely used as substitutes for cathoderay tubes (CRTs) in association with mobile image display devicesbecause LCDs have advantages of superior picture quality, lightness,slimness, and low power consumption. Various applications of LCDs arebeing developed in association with not only mobile image displaydevices such as monitors of notebook computers, but also monitors of TVsto receive and display broadcast signals, and monitors of laptopcomputers.

Successful application of such LCDs to diverse image display devicesdepends on whether or not the LCDs can realize desired high picturequality including high resolution, high brightness, large display area,and the like, while maintaining desired characteristics of lightness,slimness and low power consumption.

Hereinafter, the structure of a conventional LCD device will bedescribed with reference to the annexed drawings.

FIG. 1 is a plan view illustrating a conventional LCD provided with acolumn spacer. FIG. 2 is a sectional view taken along the line I-I′ ofFIG. 1.

As shown in FIGS. 1 and 2, a conventional LCD array region comprisesgate lines 4 and data lines 5 that intersect each other to define pixelregions, thin film transistors (TFT) each formed at an intersectionbetween the gate line 4 and the data line, and pixel electrodes 6 formedin each of the pixel regions. The array region further comprises columnspacers 20 uniformly spaced apart from one another, to maintain a cellgap. In FIG. 1, column spacers 20 are arranged at respective pixels,each of which includes three sub-pixels, i.e., R, G and B sub-pixels.

As shown in FIG. 2, each column spacer 20 is arranged in a regionprovided above the gate line 4. That is, the gate line 4 is arranged ona first substrate 1, a gate insulating film 15 is arranged over theentire surface of the first substrate 1 including the gate line 4, and apassivation film 16 is arranged on the gate insulating film 15.

Meanwhile, a second substrate 2 comprises a black matrix layer 7 toshield non-pixel regions (portions where gate lines, data lines and thinfilm transistors are formed) other than the pixel regions. In addition,R, G and B color filter layers are formed at respective pixel regions onthe second substrate 2 including the black matrix layer 7, and a commonelectrode 14 is arranged over the entire surface of the second substrate2 including the color filter layers 8.

The column spacers 20 are formed on portions of the common electrode 14corresponding to the gate lines 4. Accordingly, the first and secondsubstrates 1 and 2 are joined together such that the column spacers 20are arranged on the gate lines 4.

The column spacers 20 are formed in an array process of the firstsubstrate 1 or the second substrate 2. The column spacers 20 are fixedlyformed in the form of columns with a certain height on the predeterminedsubstrate.

The column spacers 20 are fixed in specific positions and thus do notmove, when liquid crystals are dropped to form a liquid crystal layer.Advantageously, the column spacers do not inhibit the liquid crystalsfrom flowing. However, the column spacers have a large area in contactwith the corresponding substrate, thus disadvantageously causing displaydefects, e.g., touch defects.

LCDs including the aforementioned column spacers suffer from thefollowing problems.

A region, where the liquid crystal panel of the conventional columnspacers-comprising LCDs is touched in a certain direction by hand orother objects, is stained. This stain is formed upon touch and is thusreferred to as a “touch stain”. As such, the stain is observed on thescreen and thus is also called a “touch defect”. Such a touch defect isconsidered to be attributed to the high frictional force which is causedby the large contact area between the column spacer and thecorresponding substrate, as compared to conventional ball spacerstructures. That is, because column spacers have a large area in contactwith the corresponding substrate, as compared to ball spacers, afterupper and lower substrates shift towards each other upon touching, theytake a long time to return to an original state and stains thus remainuntil they completely return to the original state.

Accordingly, efforts have made to use ball spacers in liquid crystalpanels. In these cases, the ball spacers move and deviate from theiroriginal positions in fabrication and use due to their mobility, thuscausing other problems. Research is being conducted on solving theseproblems.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a liquid crystaldisplay (LCD) device and a method for manufacturing the same thatsubstantially obviate one or more problems due to limitations anddisadvantages of the related art.

An object of the present invention is to provide a liquid crystaldisplay (LCD) device and a method for manufacturing the same, whereinafter balls are formed in an ink-jetting manner, a solid is left behindon the surface where the balls are formed, thus causing improvement ofthe adhesion force between the balls and substrates.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, aliquid crystal display device comprises: a first substrate and a secondsubstrate facing each other, wherein each of the first and secondsubstrates includes a plurality of pixel regions spaced apart from eachother to form a matrix; a black matrix layer arranged in a regionexcluding the pixel regions on the first substrate; a plurality of gatelines and a plurality of data lines crossing each other, arecorresponding to the black matrix layer on the second substrate; aplurality of spacers arranged in predetermined portions provided on theblack matrix layer between the first and second substrates, wherein eachspacer includes one or more balls, and a solid to adhere the balls tothe first or second substrate; and a liquid crystal layer filled betweenthe first substrate and the second substrate.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is a plan view illustrating a conventional liquid crystal displaydevice;

FIG. 2 is a sectional view taken along the line I-I′ of FIG. 1.

FIG. 3 is a sectional view illustrating a liquid crystal display deviceusing a ball spacer;

FIG. 4 is a sectional view illustrating a state in which the ball spacerof FIG. 3 moves upon fabrication or use;

FIGS. 5A and 5B are sectional views illustrating states of the liquidcrystal display device according to the present invention uponfabrication and use, respectively.

FIG. 6 is a flow chart illustrating a method for manufacturing a spacerof the liquid crystal display device according to the present invention;

FIG. 7 is a schematic view illustrating a head used for an ink-jettingprocess of FIG. 6;

FIGS. 8A to 8B are plan views illustrating the liquid crystal displaydevice according to exemplary embodiments of the present invention; and

FIG. 9 is a sectional view taken along the spacer of FIGS. 8A and 8B.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an LCD device and a method for manufacturing the sameaccording to the present invention will be described with reference tothe annexed drawings.

Taking into consideration the fact that the large contact area betweenconventional column spacers and the opposite substrate causes displaydefects such as touch defects, attempts have been made to solve thedefects by reducing the contact area with the opposite substrate. Ofthese attempts, a method for manufacturing ball spacers by ink-jettingwas suggested.

FIG. 3 is a sectional view illustrating a liquid crystal display deviceusing a ball spacer. FIG. 4 is a sectional view illustrating aphenomenon in which movement of the ball spacer of FIG. 2 occurs uponfabrication or use.

As shown in FIG. 3, in the liquid crystal display device using the ballspacer, the ball spacer 55 is arranged on the structure including ablack matrix layer 51, a color filter layer 52, an overcoat layer 53 andan alignment film 54 arranged on a second substrate 50 in this order.

Recently, a method in which the ball spacer 55 is dotted in a desiredposition by ink-jetting has been suggested. After the ball spacer 55 isformed in the desired position, it moves from the position due to anapplied external force during the formation process or an applied impactin use, as shown in FIG. 4, thus disadvantageously causing lightleakage. That is, when the ball spacer 55 deviates from the originalposition, it comes out of the portion provided above the black matrixlayer 51 and rolls toward the side of the portion. At this time, aheight difference between the top of the ball spacer 55 which is dottedin the initial position, and the top of the ball spacer 55 which isarranged in the final position occurs, which is substantially comparableto the thickness of the black matrix layer 51. Such a height differencemay cause variation in cell gap after the ball movement. In addition,the height difference involves problems in that an aperture ratio isdecreased due to the ball spacer 55 arranged out of regions provided bythe black matrix layer. Furthermore, the ball spacer 55 arranged in thepixel region results in distorted orientation of liquid crystal, thuscausing light leakage.

Hereinafter, a liquid crystal display and a method for manufacturing thesame, capable of solving the problems associated with formation of theball spacer, will be illustrated with reference to the annexed drawings.

FIGS. 5A and 5B are sectional views illustrating states of the liquidcrystal display device according to the present invention uponfabrication and use, respectively.

As shown in FIG. 5A, the liquid crystal display device of the presentinvention comprises: a first substrate 100 including pixel regionsspaced apart from each other to form a matrix, a black matrix layer 101arranged in a region other than the pixel regions on the first substrate100; a color filter layer 102 arranged on the black matrix layer 101 inat least portions corresponding to the pixel regions; an overcoat layer103 or a common electrode (not shown) arranged on the entire surface ofthe first substrate 100 including the black matrix layer 101 and thecolor filter layer 102; and a first alignment film 104 arranged on theovercoat layer 103 or the common electrode.

In addition, the first substrate further comprises a spacer 150 arrangedin a portion provided above the black matrix layer 101 on the firstalignment film 104, in which the spacer 150 includes balls 151 and asolid 152 to adhere the balls 151 to the first alignment film 104.

The spacer 150 is formed in accordance with an ink-jetting method, whichis performed by jetting a spacer-forming material from the head in apredetermined position on the first alignment film 104. Upon eachjetting, the head comprises a plurality of balls 151, to cause thespacer 150 to remain in the form of an aggregate in the predeterminedposition. The spacer-forming material contained in the head consists of2 to 20 wt % of a thermosetting binder in a liquid state of the solid152, 80 to 98 wt % of a solvent (not shown), and 0.1 to 3 wt % of theballs 151, with respect to the total weight of the thermosetting binderand the solvent.

In the process of such ink-jetting, the spacer-forming materialincluding the plurality of balls is jetted in the corresponding regionand then cured at about 80 to 300° C. As a result, the liquidthermosetting binder is cured and then solidified in the form of anaggregate including the plurality of balls 151, to form a solid, whilethe solvent is vaporized.

The solid is a thermosetting binder. For example, the solid includes atleast one organic compound selected from acrylic, urethane, epoxy andsilicone compounds. Examples of acrylic compounds may include ethylmethacrylate, N-butyl methacrylate, isobutyl methacrylate,dicyclopentanyl methacrylate, benzyl methacrylate, glycidylmethacrylate, 2-hydroxyethyl methacrylate, methacrylic acid isobornylmethacrylate and styrene polymers, and combinations thereof.

In addition, the spacers are formed by ink-jetting a liquid materialconsisting of the liquid thermosetting binder and the solvent, followedby curing. In the curing process, the thermosetting binder is cured,while the solvent is vaporized. The curing is carried out at 80 to 300°C.

The solvent is selected from those that have a boiling point of 60 to300° C. For example, a glycol ether may be used as the solvent. Examplesof useful glycol ethers include propylene glycol methyl ether (PGME),dipropylene glycol methyl ether (DGME), tripropylene glycol methyl ether(TGME), propylene glycol methyl ether acetate (PGMEA), dipropyleneglycol methyl ether acetate (DGMEA), propylene glycol n-propyl ether(PGPE), dipropylene glycol n-propyl ether (DGPE), propylene glycoln-butyl ether (PGBE), dipropylene glycol n-butyl ether (DCBE),tripropylene glycol n-butyl ether (TGBE), propylene glycol phenyl ether(PGPE), propylene glycol diacetate (PGD), dipropylene glycol dimethylether (DGDE), diethylene glycol ethyl ether (DGEE), diethylene glycolmethyl ether (DGME), diethylene glycol n-butyl ether (DGBE), diethyleneglycol hexyl ether (DGHE), diethylene glycol n-butyl ether acetate(DGBEA), ethylene glycol propyl ether (EGPE), ethylene glycol n-butylether (EGBE), ethylene glycol hexyl ether (EGHE), ethylene glycoln-butyl ether acetate (EGBEA), triethylene glycol methyl ether (TGME),triethylene glycol ethyl ether (TGEE), triethylene glycol n-butyl ether(TGBE), ethylene glycol phenyl ether (EGPE) and ethylene glycol n-butylether mixtures (EGBEM).

Preferably, the solvent has a surface tension of 20 to 80 dynes/cm, aviscosity of 1 to 30 cP and a density of 0.8 to 1.2 g/cc at ambienttemperature. Based on these properties, the solvent is vaporized andremoved during curing at about 80 to 300° C.

In addition, the balls 151 are made of an organic compound e.g.divinylbenzene. The balls 151 can be distinguished from otheringredients, in that the balls 151 are present in the form of a whitepowder, while the solid and the solvent are in a liquid state. Ifnecessary, the balls 151 may be subjected to surface-treatment prior tobeing mixed to form the spacer-forming material so that they can bedistinguished from other liquid components.

As shown in the drawings, the spacer 150 may be formed on the firstalignment film 104. Alternatively, in reverse, after the spacer isformed on the overcoat layer 203 or the common electrode, the firstalignment film 104 may be formed on the overcoat layer 103 or the commonelectrode.

The spacer 150 has a height that corresponds to a cell gap between thefirst substrate 100 and the second substrate (not shown, please refer toreference numeral “200” in FIG. 9), which is comparable to the diameterof the balls 151 contained therein. Each spacer 150 may include one ball151 or may take the form of an aggregate including a plurality of balls151.

When the spacer 150 is composed of the plurality of balls 151, it has atwo-dimensional oval-like shape within the range of the width of theblack matrix layer 101. That is, the number of the balls 151 increasestowards the center of the spacer, and on the other hand, the number ofthe balls 151 decreases towards the edge of the spacer. The solid 152prevents the jetted balls 151 from being dispersed in the portion wherethe spacer 150 is to be formed, instead being aggregated. Thus, thesolid 152 functions to fix the balls 151 on the first alignment film 104or the overcoat layer. The spacer 150 has an oblate shape, because thespacer-forming material is in a liquid state upon jetting, and is thuspartially spread in the jetted portion.

Meanwhile, the color filter layer 102 may be arranged on the blackmatrix layer 101 in pixel regions, as shown in the drawings. In somecases, the color filter layer 102 may be selectively arranged only inpixel regions, or partially overlapped with the black matrix layer 101in the portion provided by the black matrix layer 101.

Although not illustrated, the second substrate 200 that faces the firstsubstrate 100 includes a plurality of gate lines and a plurality of datalines such that the gate lines and the data lines intersect each otherto define pixel regions corresponding to the black matrix layer 101;thin film transistors (TFTs) located at each intersection of anassociated data line and gate line; and pixel electrodes arranged in therespective pixel regions. A detailed explanation thereof will beprovided with reference to FIGS. 8A and 8B, and 9.

Referring to FIG. 5B, even if impact occurs in the process of joiningthe first substrate 100 including the spacer 150 to the oppositesubstrate, assembling the substrates, or using the substrates, the solid152 is cured while maintaining its jetted state, without movement of theballs, thus allowing the balls 151 to remain adhered to the firstsubstrate 100. As a result, light leakage caused by movement of theballs, or display defects due to variation in cell gap can be prevented.

Furthermore, the spacer 150 is in contact with the opposite substrateonly through the surface of the ball 151. Accordingly, the spacer 150has a dot-like narrow area in contact with the opposite substrate.Consequently, although upon touching, the two substrates shift towardseach other, the frictional force generated thereby can be reduced, thusmaking the substrates rapidly return to their original states. As aresult, display defects such as touch defects can be prevented.

FIG. 6 is a flow chart illustrating a method for manufacturing a spacerof the liquid crystal display device according to the present invention.FIG. 7 is a schematic view illustrating a head used for an ink-jettingprocess of FIG. 6.

As shown in FIGS. 6 and 7, in the liquid crystal display device of thepresent invention, the spacers are formed by jetting a predeterminedamount of spacer material 160 through nozzles (not shown) provided in anink-jet head 300 at one or more pixels on the substrate. At this time,by controlling the distance between the nozzles, each time jetting isperformed in a predetermined portion, a plurality of the balls 151contained in the spacer material 160 can be jetted therein.

At this time, as shown in FIG. 7, the inkjet head 300 contains thespacer material. The spacer material contained in the inkjet head 300comprises: 1 to 20 wt % of a liquid thermosetting binder 152 and 80 to98 wt % of a solvent 153, each being present in a liquid state; and 0.1to 3 wt % of the balls 151, with respect to 100 wt % of the total weightof the thermosetting binder 152 and the solvent 153.

The spacer components, i.e., the balls, the liquid thermosetting binderand the solvent are the same as mentioned above.

FIGS. 8A and 8B are plan views illustrating liquid crystal displaydevices according to preferred embodiments of the present invention.FIG. 9 is a sectional view taken along the spacer parallel to the dataline of FIGS. 8A and 8B.

FIG. 8A is a plan view illustrating a twisted nematic (TN) mode liquidcrystal display device. FIG. 8B is a plan view illustrating an in-planeswitching (IPS) mode liquid crystal display device. TN and IPS mode LCDsare identical to each other, except that the structure provided on afirst substrate 100 arranged above a liquid crystal layer (not shown) iseither an overcoat layer 103 or a common electrode (not shown). In somecases, TN mode LCDs may include both the overcoat layer and the commonelectrode.

Hereinafter, TN and IPS mode liquid crystal display devices will beillustrated in this order.

As shown in FIG. 8A and 9, in the TN mode LCD, the first substrate 100comprises a black matrix layer 101 to shield light to regions (i.e.,portions corresponding to the gate lines, the data lines and the thinfilm transistors) other than the pixel regions; R, G and B color filterlayers 102 to render colors in the corresponding pixel regions; and acommon electrode 103 arranged over the entire surface of the blackmatrix layer 101 and the color filter layers 102. In addition, the firstsubstrate 100 further comprises a first alignment film 104 arranged overthe entire surface of the common electrode 103, and spacers 150 arrangedin the form of aggregates including balls 151 and a solid 152 on thefirst alignment film 104. In some cases, the spacers 150 may be arrangedon the second substrate 200.

The step of forming the spacers 150 comprises jetting a spacer-formingmaterial 160 consisting of the balls 151, the liquid thermosettingbinder liquidized from the solid 152 and the solvent 153 inpredetermined portions, followed by heating. In the process of heating,the liquid thermosetting binder is adhered to the first substrate 100 orthe second substrate 200 adjacent to the balls 151 and then cured, toform a solid, while the solvent 153 is vaporized.

The curing is carried out by heating at 80 to 300° C.

The liquid thermosetting binder includes at least one organic compoundselected from acrylic, urethane and epoxy compounds. Alternatively, theliquid thermosetting binder may include a silicone compound.

The solvent 153 is selected from those that have a boiling point of 60to 300° C. For example, glycol ether may be used as the solvent.Examples of useful glycol ethers include propylene glycol methyl ether(PGME), dipropylene glycol methyl ether (DGME), tripropylene glycolmethyl ether (TGME), propylene glycol methyl ether acetate (PGMEA),dipropylene glycol methyl ether acetate (DGMEA), propylene glycoln-propyl ether (PGPE), dipropylene glycol n-propyl ether (DGPE),propylene glycol n-butyl ether (PGBE), dipropylene glycol n-butyl ether(DGBE), tripropylene glycol n-butyl ether (TGBE), propylene glycolphenyl ether (PGPE), propylene glycol diacetate (PGD), dipropyleneglycol dimethyl ether (DGDE), diethylene glycol ethyl ether (DGEE),diethylene glycol methyl ether (DGME), diethylene glycol n-butyl ether(DGBE), diethylene glycol hexyl ether (DGHE), diethylene glycol n-butylether acetate (DGBEA), ethylene glycol propyl ether (EGPE), ethyleneglycol n-butyl ether (EGBE), ethylene glycol hexyl ether (EGHE),ethylene glycol n-butyl ether acetate (EGBEA), triethylene glycol methylether (TGME), triethylene glycol ethyl ether (TGEE), triethylene glycoln-butyl ether (TGBE), ethylene glycol phenyl ether (EGPE) and ethyleneglycol n-butyl ether mixtures (EGBEM).

Preferably, the solvent 153 has a surface tension of 20 to 80 dynes/cm,a viscosity of 1 to 30 cP and a density of 0.8 to 1.2 g/cc at ambienttemperature. Based on these properties, the solvent 153 is vaporized andremoved during curing.

With respect to the composition of the spacer material 160, the spacermaterial 160 comprises: a liquid component consisting of 1 to 20 wt % ofthe liquid thermosetting binder, and the remaining weight, i.e., 80 to98 wt %, of the solvent; and 0.1 to 3 wt % of the balls, with respect to100 wt % of the total weight of the liquid component.

The second substrate 200 that faces the first substrate 100 comprisesgate lines 201 and data lines 202 arranged on the second substrate 200that intersect each other to define pixel regions, pixel electrodes 203formed in the respective pixel regions, and thin film transistors (TFT)formed at respective intersections between the gate lines 101 and thedata lines 202.

The second substrate further comprises spacers 150 arranged such thatthey are within the width of the gate lines 201 or the data lines 202.As shown in the drawings, spacers 150 are arranged on the gate lines201.

Hereinafter, a method for manufacturing the thin film transistors andthe pixel electrodes will be illustrated in detail.

A metal such as Mo, Al or Cr is deposited on a second substrate 200 andis then patterned through photolithographic processes to simultaneouslyform a plurality of gate lines 201 and gate electrodes 201 a.

Each gate electrode 201 a is formed in a protrusion shape protruded froman associated one of the gate lines 201 in a predetermined positionprovided by each pixel region.

An insulating material such as SiN_(x) is then deposited over the entiresurface of the second substrate 200 including the gate lines 201 and thegate electrodes 201 a, to form a gate insulating film 211. Asemiconductor layer material is deposited over the gate insulating film211 and is then patterned to form a semiconductor layer 214 on the gateinsulating film 211 arranged on the gate electrode 201 a.

The formation of the semiconductor layer 214 is achieved by sequentiallydepositing an amorphous silicon layer (or a polysilicon layer) and asilicon layer heavily doped with an impurity, and simultaneouslypatterning the amorphous silicon layer (or the polysilicon layer) andthe doped silicon layer.

Subsequently, a metal material such as Mo, Al, or Cr is deposited overthe entire surface of the resulting structure and is then patternedthrough photolithographic processes, to form data lines 202 such thatthey expand perpendicular to the gate lines 201, and source electrodes202 a and drain electrodes 202 b such that they are in contact withopposite sides of the semiconductor layer 214. The doped silicon layerwhich is in the space between the source electrode 202 a and the drainelectrode 202 b is removed.

Each source electrode 202 a has a protrusion shape protruded from anassociated one of the data lines 202.

Thereafter, a passivation film 212 is deposited over the entire surfaceof the resulting structure including the source and drain electrodes 202a and 202 b.

For the material of the passivation film 212, an inorganic material suchas SiN_(x) is conventionally used. However, an organic material having alow dielectric constant, such as benzocyclobutene (BCB), spin-on-glass(SOG), or acryl resin, has recently been used to achieve an enhancementin the aspect ratio of liquid crystal cells.

Subsequently, the portion of the passivation film 212 arranged on eachdrain electrode 202 b is selectively etched, to form a drain contacthole, through which the drain electrode 202 b is partially exposed.

Next, a transparent insulating film is deposited over the passivationfilm 212 such that it is in electrical contact with the drain electrode202 b through the drain contact hole, and is then selectively removedsuch that only the pixel region remains, to from a pixel electrode 203.

A second alignment film 213 is formed over the passivation film 212including the pixel electrode 203.

Optionally, the first and second alignment films 104 and 213 may beformed or not formed.

An example where the liquid crystal display device of the presentinvention is applied to an IPS mode LCD will be illustrated in detailwith reference to FIGS. 8B and 9.

The IPS mode LCD device according to the present invention comprises: ablack matrix layer 101 arranged on the first substrate 100 to shieldlight to regions (i.e., portions corresponding to the gate lines, thedata lines and the thin film transistors) other than the pixel regions;R, G and B color filter layers 102 to render colors in the correspondingpixel regions; and an overcoat layer 103 arranged over the entiresurface of the black matrix layer 101 and the color filter layers 102.

A first alignment film 104 is arranged on the overcoat layer 103 andspacers 150 are arranged in regions provided by the black matrix layer101 on the first alignment film 104. Here, the spacers are formed inaccordance with the process as mentioned above.

A plurality of gate lines 201 and a plurality of data lines 202 arearranged on the second substrate 200 that faces the first substrate 100,such that the gate lines 201 and the data lines 202 intersect eachother, to define pixel regions. In addition, common lines 215 a arearranged on the second substrate 200 such that the common lines extendin parallel to the gate lines 201. Common electrodes 215 are protrudedfrom the common lines 215 a in respective pixels such that they areuniformly spaced apart from each other. In addition, thin filmtransistors (TFTs) including source/drain electrodes 202 a and 202 b arelocated at respective intersections of the gate lines 201 and the datalines 202. Pixel electrodes 216 expand parallel to the common electrodes215 between the common electrodes at respective pixels, while beingconnected to the drain electrodes 202 b of the thin film transistors.

Hereinafter, a method for manufacturing the thin film transistors, thecommon electrodes and the pixel electrodes will be illustrated indetail.

A metal such as Mo, Al or Cr is deposited on the second substrate 200and is then patterned through photolithographic processes tosimultaneously form a plurality of gate lines 201, gate electrodes 201a, common lines 215 a and common electrodes 215.

Each gate electrode 201 a is formed in a protrusion shape protruded froman associated one of the gate lines 201 in a predetermined positionprovided by each pixel region.

An insulating material such as SiN_(x) is then deposited over the entiresurface of the second substrate 200 including the gate lines 201, thecommon lines 215 a, the gate electrodes 210 a and the common electrodes215, to form a gate insulating film 211. A semiconductor layer isdeposited over the gate insulating film 211 and then patterned to form asemiconductor layer 214 on the gate insulating film 211 arranged on thegate electrode 201 a.

The formation of the semiconductor layer 214 is achieved by sequentiallydepositing an amorphous silicon layer (or a polysilicon layer) and asilicon layer heavily doped with an impurity, and simultaneouslypatterning the amorphous silicon layer (or the polysilicon layer) andthe doped silicon layer.

Subsequently, a metal material such as Mo, Al, or Cr is deposited overthe entire surface of the resulting structure and then patterned throughphotolithographic processes, to form data lines 202 such that theyexpand perpendicular to the gate lines 201, and source electrodes 202 aand drain electrodes 202 b such that they are in contact with oppositesides of the semiconductor layer 214. The doped silicon layer which isin the space between the source electrode 202 a and the drain electrode202 b is removed.

Each source electrode 202 a has a protrusion shape protruded from anassociated one of the data lines 202.

Thereafter, a passivation film 212 is deposited over the entire surfaceof the second substrate 200 including the source and drain electrodes202 a and 202 b.

For the material of the passivation film 212, an inorganic material suchas SiN_(x) is conventionally used. However, an organic material having alow dielectric constant, such as benzocyclobutene (BCB), spin-on-glass(SOG), or an acryl resin, has recently been used to achieve anenhancement in the aspect ratio of liquid crystal cells.

Subsequently, the portion of the passivation film 212 arranged on eachdrain electrode 202 b is selectively etched, to form a drain contacthole, through which the drain electrode 202 b is partially exposed.

Next, a transparent electrode material is deposited over the passivationfilm 212 and is then selectively removed, to form pixel electrodes 216alternately formed with the common electrodes 215 at respective pixels.

For the afore-mentioned IPS mode LCD device, the common and pixelelectrodes are formed of different materials (i.e., the common electrodeis made of a metal and the pixel electrode is made of a transparentelectrode) on the different layers. Alternatively, the common electrodeand the pixel electrode may be formed of the same transparent electrodematerial on the same layer.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A liquid crystal display device comprising: a first substrate and asecond substrate facing each other, wherein each of the first and secondsubstrates includes a plurality of pixel regions spaced apart from eachother to form a matrix; a black matrix layer arranged in a regionexcluding the pixel regions on the first substrate; a plurality of gatelines and a plurality of data lines crossing each other, arecorresponding to the black matrix layer on the second substrate; aplurality of spacers arranged in predetermined portions provided on theblack matrix layer between the first and second substrates, wherein eachof the plurality of spacers includes one or more balls, and a solid toadhere the one or more balls to the first or second substrate andwherein the solid is formed of at least one of organic acrylic compoundand urethane; and a liquid crystal layer filled between the firstsubstrate and the second substrate, wherein the organic acrylic compoundincludes ethyl methacrylate, N-butyl methacrylate, isobutylmethacrylate, dicyclopentanyl methacrylate, benzyl methacrylate,glycidyl methacrylate, 2-hydroxyethyl methacrylate, methacrylic acidisobornyl methacrylate and styrene polymers, and combinations thereof.2. The liquid crystal display device according to claim 1, wherein theplurality of spacers are formed by ink-jetting a spacer-forming materialcomprising the balls, a thermosetting binder liquidized from the solid,and the solvent, followed by curing, wherein in the process of curing,the thermosetting binder is cured, while the solvent is vaporized. 3.The liquid crystal display device according to claim 2, wherein thecuring is carried out at 80 to 300° C.
 4. The liquid crystal displaydevice according to claim 1, wherein the balls are aggregated togetherby aid of the solid.
 5. The liquid crystal display device according toclaim 1, wherein the plurality of spacers comprising the one or moreballs and the solid are formed in portions provided on the plurality ofgate lines or the plurality of data lines, and a width of the spacers issmaller than a width of the plurality of gate lines or the plurality ofdata lines.
 6. The liquid crystal display device according to claim 1,further comprising: a color filter layer formed on the second substrateincluding the black matrix layer; and an overcoat layer or a commonelectrode formed on the color filter layer.
 7. The liquid crystaldisplay device according to claim 6, further comprising: a firstalignment film formed on the overcoat layer or the common electrode; anda second alignment film formed on the second substrate including theplurality of gate lines or the plurality of data lines.
 8. The liquidcrystal display device according to claim 7, wherein the plurality ofspacers are formed on the first alignment film.
 9. The liquid crystaldisplay device according to claim 7, wherein the first alignment film isformed on the plurality of spacers.